In the field of mass transport, trams that run on guideways are known, particularly at airports for conveying passengers from one terminal to another. Typically, the guideway has a steering rail and power conductors. Normally each tram unit has front and rear wheels, and at least the lead unit has an electrical motor for supplying power to the wheels. The tram receives its power and steering control from the guideway system. These guideway passenger trams are not equipped to be driven by an operator on a conventional roadway.
Operator driven, manually steerable trams have also been used in the past for conveying people, such as from large parking areas to an arena, or conveying people around a fair, a zoo, or a theme park. These trams comprise a tractor or lead vehicle that has its onboard power source, typically a gasoline or diesel engine. The trailing units are connected by hitches to each other and towed by the lead vehicle. These trams are not suitable for automatic operation on a guideway. Also because of the wide turn radius, they are not normally driven on a conventional street.
Cargo transport systems that include tractors that tow two or more trailers on conventional roadways are known. The tractor or truck supplies the power, and an operator controls the steering, speed and brakes. Often the first trailer is connected to the tractor by a fifth wheel arrangement, thus will have only a rear set of wheels. The second trailer usually has both front and rear sets of wheels. These cargo transport units are not capable of automatic operation on a guideway system. Furthermore, it is difficult to operate a truck with tandem trailers on city streets because of the wide radius of turn that would be required.